ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Climate-driven changes in biomass allocation in pines (2000)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 6 (2000), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Future increases in air temperature resulting from human activities may increase the water vapour pressure deficit (VPD) of the atmosphere. Understanding the responses of trees to spatial variation in VPD can strengthen our ability to predict how trees will respond to temporal changes in this important variable. Using published values, we tested the theoretical prediction that conifers decrease their investment in photosynthetic tissue (leaves) relative to water-conducting tissue in the stem (sapwood) as VPD increases. The ratio of leaf/sapwood area (AL/AS) decreased significantly with increasing VPD in Pinus species but not in Abies, Pseudotsuga, Tsuga and Picea, and the average AL/AS was significantly lower for pines than other conifers (pines: 0.17 m2 cm−2; nonpines: 0.44 m2 cm−2). Thus, pines adjusted to increasing aridity by altering above-ground morphology while nonpine conifers did not. The average water potential causing a 50% loss of hydraulic conductivity was −3.28 MPa for pines and −4.52 MPa for nonpine conifers, suggesting that pines are more vulnerable to xylem embolism than other conifers. For Pinus ponderosa the decrease in AL/AS with high VPD increases the capacity to provide water to foliage without escalating the risk of xylem embolism. Low AL/AS and plasticity in this variable may enhance drought tolerance in pines. However, lower AL/AS with increasing VPD and an associated shift in biomass allocation from foliage to stems suggests that pines may expend more photosynthate constructing and supporting structural mass and carry less leaf area as the climate warms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.2000.00338.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    First-year growth response of trees in an intact forest exposed to elevated CO2 (1999)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 5 (1999), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Although elevated atmospheric CO2 has been shown to increase growth of tree seedlings and saplings, the response of intact forest ecosystems and established trees is unclear. We report results from the first large-scale experimental system designed to study the effects of elevated CO2 on an intact forest with the full complement of species interactions and environmental stresses. During the first year of exposure to ^ 1.5 Ë ambient CO2, canopy loblolly pine (Pinus taeda, L.) trees increased basal area growth rate by 24% but understorey trees of loblolly pine, sweetgum (Liquidambar styraciflua L.), and red maple (Acer rubrum L.) did not respond. Winged elm (Ulmus alata Michx.) had a marginally significant increase in growth rate (P = 0.069). These data suggest that this ecosystem has the capacity to respond immediately to a step increase in atmospheric CO2; however, as exposure time increases, nutrient limitations may reduce this initial growth stimulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.1999.00256.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Primary productivity of planet earth: biological determinants and physical constraints in terrestrial and aquatic habitats (2001)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 7 (2001), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.2001.00448.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    The contribution of bryophytes to the carbon exchange for a temperate rainforest (2003)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 9 (2003), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Bryophytes blanket the floor of temperate rainforests in New Zealand and may influence a number of important ecosystem processes, including carbon cycling. Their contribution to forest floor carbon exchange was determined in a mature, undisturbed podocarp-broadleaved forest in New Zealand, dominated by 100–400-year-old rimu (Dacrydium cupressimum) trees. Eight species of mosses and 13 species of liverworts contributed to the 62% cover of the diverse forest floor community. The bryophyte community developed a relatively thin (depth 〈30 mm), but dense, canopy that experienced elevated CO2 partial pressures (median 46.6 Pa immediately below the bryophyte canopy) relative to the surrounding air (median 37.6 Pa at 100 mm above the canopy). Light-saturated rates of net CO2 exchange from 14 microcosms collected from the forest floor were highly variable; the maximum rate of net uptake (bryophyte photosynthesis – whole-plant respiration) per unit ground area at saturating irradiance was 1.9 μmol m−2 s−1 and in one microcosm, the net rate of CO2 exchange was negative (respiration). CO2 exchange for all microcosms was strongly dependent on water content. The average water content in the microcosms ranged from 1375% when fully saturated to 250% when air-dried. Reduction in water content across this range resulted in an average decrease of 85% in net CO2 uptake per unit ground area.The results from the microcosms were used in a model to estimate annual carbon exchange for the forest floor. This model incorporated hourly variability in average irradiance reaching the forest floor, water content of the bryophyte layer, and air and soil temperature. The annual net carbon uptake by forest floor bryophytes was 103 g m−2, compared to annual carbon efflux from the forest floor (bryophyte and soil respiration) of −1010 g m−2. To put this in perspective of the magnitude of the components of CO2 exchange for the forest floor, the bryophyte layer reclaimed an amount of CO2 equivalent to only about 10% of forest floor respiration (bryophyte plus soil) or ∼11% of soil respiration. The contribution of forest floor bryophytes to productivity in this temperate rainforest was much smaller than in boreal forests, possibly because of differences in species composition and environmental limitations to photosynthesis. Because of their close dependence on water table depth, the contribution of the bryophyte community to ecosystem CO2 exchange may be highly responsive to rapid changes in climate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.2003.00650.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Consequences of wildfire on ecosystem CO2 and water vapour fluxes in the Great Basin (2003)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 9 (2003), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Increased fire frequency in the Great Basin of North America's intermountain West has led to large-scale conversion of native sagebrush (Artemisia tridentata Nutt.) communities to postfire successional communities dominated by native and non-native annual species during the last century. The consequences of this conversion for basic ecosystem functions, however, are poorly understood. We measured net ecosystem CO2 exchange (NEE) and evapotranspiration (ET) during the first two dry years after wildfire using a 4-m diameter (16.4 m3) translucent static chamber (dome), and found that both NEE and ET were higher in a postfire successional ecosystem (−0.9–2.6 µmol CO2 m−2 s−1 and 0.0–1.0 mmol H2O m−2 s−2, respectively) than in an adjacent intact sagebrush ecosystem (−1.2–2.3 µmol CO2 m−2 s−1 and −0.1–0.8 mmol H2O m−2 s−2, respectively) during relatively moist periods. Higher NEE in the postfire ecosystem appears to be due to lower rates of above-ground plant respiration while higher ET appears to be caused by higher surface soil temperatures and increased soil water recharge after rains. These patterns disappeared or were reversed, however, when the conditions were drier. Daily net ecosystem productivity (NEP; g C m−2 d−1), derived from multiple linear regressions of measured fluxes with continuously measured climate variables, was very small (close to zero) throughout most of the year. The wintertime was an exception in the intact sagebrush ecosystem with C losses exceeding C gains leading to negative NEP while C balance of the postfire ecosystem remained near zero. Taken together, our results indicate that wildfire-induced conversion of native sagebrush steppe to ecosystems dominated by herbaceous annual species may have little effect on C balance during relatively dry years (except in winter months) but may stimulate water loss immediately following fires.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.2003.00600.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    The contribution of drought-related decreases in foliar nitrogen concentration to decreases in photosynthetic capacity during and after drought in prairie grasses (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 101 (1997), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: While stomatal closure usually limits photosynthesis during drought, our previous results suggest that drought-related decreases in foliar nitrogen concentration (NL) limit photosynthesis during recovery from drought in prairie grasses. Here we estimate the importance of decreases in NL to decreased photosynthetic capacity (PScap) during drought and a subsequent recovery period in three perennial C4 prairie grasses. PScap (O2 evolution at light and CO2 saturation) decreased 69 to 78% during drought in these grasses, and full recovery of PScap required 8 to 12 days, until younger leaves were expanded or older leaves were repaired, depending on species. Decreases in NL explained 38 to 51% of the loss of PScap during drought and accounted for 51 to 69% of the total loss of PScap integrated over the post-drought recovery period. N-related loss of PScap appeared to result more from decreases in ribulose-1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39), phosphoenolpyruvate carboxylase (4.1.1.31), and other soluble photosynthetic enzymes, than from decreases in thylakoid N-containing compounds. Decreases in quantum yield of O2 evolution and Fv/Fm (variable-to-maximum fluorescence of dark-adapted leaves) during drought were small, so we assumed that little damage to photsystem II (PSII) and thylakoid membrane function occurred. Further, F0 (minimum F) decreased or remained unchanged, dark F0 was greater than light F0, and decreases in photochemical quenching (the fraction of oxidized PSII) were reversed within 1–3 days after drought. Therefore, prolonged increases in non-photochemical quenching (qn; thermal dissipation of excess light energy) during and after drought were indicative of protective downregulation and were likely associated with disproportionate loss of soluble photosynthetic proteins during drought. In support of this, post-drought recovery of qn paralleled recovery of NL and PScap. Thus, in C4 prairie grasses, loss of PScap during drought is largely the result of decreases in shoot NL and of associated protective downregulation, decreasing carbon assimilation for 1–2 weeks after drought.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1997.tb01834.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Canopy development of a model herbaceous community exposed to elevated atmospheric CO2 and soil nutrients (2001)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 113 (2001), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: To test the prediction that elevated CO2 increases the maximum leaf area index (LAI) through a stimulation of photosynthesis, we exposed model herbaceous communities to two levels of CO2 crossed with two levels of soil fertility. Elevated CO2 stimulated the initial rate of canopy development and increased cumulative LAI integrated over the growth period, but it had no effect on the maximum LAI. In contrast to CO2, increased soil nutrient availability caused a substantial increase in maximum LAI. Elevated CO2 caused a slight increase in leaf area and nitrogen allocated to upper canopy layers and may have stimulated leaf turnover deep in the canopy. Gas exchange measurements of intact communities made near the time of maximum LAI indicated that soil nutrient availability, but not CO2 enrichment, caused a substantial stimulation of net ecosystem carbon exchange. These data do not support our prediction of a higher maximum LAI by elevated CO2 because the initial stimulation of LAI diminished by the end of the growth period. However, early in development, leaf area and carbon assimilation of communities may have been greatly enhanced. These results suggest that the rate of canopy development in annual communities may be accelerated with future increases in atmospheric CO2 but that maximum LAI is set by soil fertility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2001.1130214.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Ammonia volatilization during drought in perennial C4 grasses of tallgrass prairie (1995)
    Springer
    Oecologia 101 (1995), S. 361-365 
    Details
    ISSN: 1432-1939
    Keywords: Ammonia volatilization ; Drought ; Nitrogen Prairie grasses ; Retranslocation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We measured foliar NH3 volatilization as part of our study of the decrease (up to 40%) in shoot N concentration during drought in three perennial C4 grasses of tallgrass prairie. Volatilization of recently expanded leaves was quantified using cuvettes and acid traps for Spartina pectinata, Andropogon gerardii, and Schizachyrium scoparium, a mesic, intermediate, and xeric species, respectively. In general, volatilization decreased during drought, approaching zero as stomates closed, and increased with plant N status and drought tolerance. Prior to drought, NH3 volatilization was greater in xeric than mesic species (179 and 131 vs. 115 ng m-2 s-1 for individual leaves of S. scoparium and A. gerardii vs. Sp. pectinata). During a 2–3 week drought, whole-shoot volatile N losses can exceed 5% of total plant N in these species, accounting for 2–10% of the decrease in shoot percent N (again, xeric 〉 mesic). Drought-induced N retranslocation of shoot N to roots and rhizomes is responsible for c. 63% of the decrease in percent N in Sp. pectinata, 28% in A. gerardii, and 8% in S. scoparium. The remainder of the decrease in percent N is attributable to growth dilution of existing shoot N, accounting for 34, 65, and 87% of the decrease in shoot percent N during drought in Sp. pectinata, A. gerardii, and S. scoparium, respectively. Thus, the relative importance of volatilization, retranslocation, and dilution in decreasing foliar percent N during drought in prairie grasses is species dependent and related to drought tolerance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00328823
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Stem respiration of ponderosa pines grown in contrasting climates: implications for global climate change (1997)
    Springer
    Oecologia 111 (1997), S. 19-25 
    Details
    ISSN: 1432-1939
    Keywords: Key words Climate change  ;  Construction cost  ;  Maintenance respiration  ;  Pinus ponderosa  ;  Stem respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We examined the effects of climate and allocation patterns on stem respiration in ponderosa pine (Pinus ponderosa) growing on identical substrate in the cool, moist Sierra Nevada mountains and the warm, dry, Great Basin Desert. These environments are representative of current climatic conditions and those predicted to accompany a doubling of atmospheric CO2, respectively, throughout the range of many western north American conifers. A previous study found that trees growing in the desert allocate proportionally more biomass to sapwood and less to leaf area than montane trees. We tested the hypothesis that respiration rates of sapwood are lower in desert trees than in montane trees due to reduced stem maintenance respiration (physiological acclimation) or reduced construction cost of stem tissue (structural acclimation). Maintenance respiration per unit sapwood volume at 15°C did not differ between populations (desert: 6.39 ± 1.14 SE μmol m−3 s−1, montane: 6.54 ± 1.13 SE μmol m−3 s−1, P = 0.71) and declined with increasing stem diameter (P = 0.001). The temperature coefficient of respiration (Q 10) varied seasonally within both environments (P = 0.05). Construction cost of stem sapwood was the same in both environments (desert: 1.46 ± 0.009 SE g glucose g−1 sapwood, montane: 1.48 ± 0.009 SE glucose g−1 sapwood, P = 0.14). Annual construction respiration calculated from construction cost, percent carbon and relative growth rate was greater in montane populations due to higher growth rates. These data provide no evidence of respiratory acclimation by desert trees. Estimated yearly stem maintenance respiration was greater in large desert trees than in large montane trees because of higher temperatures in the desert and because of increased allocation of biomass to sapwood. By analogy, these data suggest that under predicted increases in temperature and aridity, potential increases in aboveground carbon gain due to enhanced photosynthetic rates may be partially offset by increases in maintenance respiration in large trees growing in CO2-enriched atmospheres.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050203
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Hydraulic adjustment of maple saplings to canopy gap formation (1997)
    Springer
    Oecologia 112 (1997), S. 472-480 
    Details
    ISSN: 1432-1939
    Keywords: Key words Hydraulic conductivity ; Biomass allocation ; Transpiration ; Acerrubrum ; Acerpensylvanicum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The leaf-specific hydraulic conductivity (K L) of plant stems can control leaf water supply. This property is influenced by variation in leaf/sapwood area ratio (A L/A S) and the specific hydraulic conductivity of xylem tissue (K S). In environments with high atmospheric vapor pressure deficit (VPD), K L may increase to support higher transpiration rates. We predicted that saplings of Acerrubrum and A.pensylvanicum grown in forest canopy gaps, under high light and VPD, would have higher K L and lower A L/A S than similar sized saplings in the understory. Leaf-specific hydraulic conductivity and K S increased with sapling size for both species. In A. rubrum, K S did not differ between the two environments but lower A L/A S (P=0.05, ANCOVA) led to higher K L for gap-grown saplings (P 〈 0.05, ANCOVA). In A. pensylvanicum, neither K S, A L/A S, nor KL differed between environments. In a second experiment, we examined the impact of sapling size on the water relations and carbon assimilation of A.pensylvanicum. Maximum stomatal conductance for A.pensylvanicum increased with K L (r 2=0.75, P 〈 0.05). A hypothetical large A. pensylvanicum sapling (2 m tall) had 2.4 times higher K L and 22 times greater daily carbon assimilation than a small (1 m tall) sapling. Size-related hydraulic limitations in A.pensylvanicum caused a 68% reduction in daily carbon assimilation in small saplings. Mid-day water potential increased with A.pensylvanicum sapling size (r 2=0.69, P 〈 0.05). Calculations indicated that small A.pensylvanicum saplings (low K L) could not transpire at the rate of large saplings (high K L) without reaching theoretical thresholds for xylem embolism induction. The coordination between K L and stomatal conductance in saplings may prevent xylem water potential from reaching levels that cause embolism but also limits transpiration. The K S of the xylem did not vary across environments, suggesting that altering biomass allocation is the primary mechanism of increasing K L. However, the ability to alter aboveground biomass allocation in response to canopy gaps is species-specific. As a result of the increase in K L and K S with sapling size for both species, hydraulic limitation of water flux may impose a greater restriction on daily carbon assimilation for small saplings in the gap environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050334
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...